Module PS.Dsc

This function indicates that subsequent calls to Cairo.PS.Dsc.comment should direct comments to the Setup section of the PostScript output.

This function should be called at most once per surface, and must be called before any call to Cairo.PS.Dsc.begin_page_setup and before any drawing is performed to the surface.

See Cairo.PS.Dsc.comment for more details.

This function indicates that subsequent calls to Cairo.PS.Dsc.comment should direct comments to the PageSetup section of the PostScript output.

This function call is only needed for the first page of a surface. It should be called after any call to Cairo.PS.Dsc.begin_setup and before any drawing is performed to the surface.

See Cairo.PS.Dsc.comment for more details.

Emit a comment into the PostScript output for the given surface.

The comment is expected to conform to the PostScript Language Document Structuring Conventions (DSC). Please see that manual for details on the available comments and their meanings. In particular, the %IncludeFeature comment allows a device-independent means of controlling printer device features. So the PostScript Printer Description Files Specification will also be a useful reference.

The comment string must begin with a percent character (%) and the total length of the string (including any initial percent characters) must not exceed 255 characters. Violating either of these conditions will raise en exception. But beyond these two conditions, this function will not enforce conformance of the comment with any particular specification.

The comment string should not have a trailing newline.

The DSC specifies different sections in which particular comments can appear. This function provides for comments to be emitted within three sections: the header, the Setup section, and the PageSetup section. Comments appearing in the first two sections apply to the entire document while comments in the BeginPageSetup section apply only to a single page.

For comments to appear in the header section, this function should be called after the surface is created, but before a call to Cairo.PS.Dsc.begin_setup.

For comments to appear in the Setup section, this function should be called after a call to Cairo.PS.Dsc.begin_setup but before a call to Cairo.PS.Dsc.begin_page_setup.

For comments to appear in the PageSetup section, this function should be called after a call to Cairo.PS.Dsc.begin_page_setup.

Note that it is only necessary to call Cairo.PS.Dsc.begin_page_setup for the first page of any surface. After a call to Cairo.show_page or Cairo.copy_page comments are unambiguously directed to the PageSetup section of the current page. But it doesn't hurt to call this function at the beginning of every page as that consistency may make the calling code simpler.

As a final note, cairo automatically generates several comments on its own. As such, applications must not manually generate any of the following comments:

• Header section: %!PS-Adobe-3.0, %Creator, %CreationDate, %Pages, %BoundingBox, %DocumentData, %LanguageLevel, %EndComments.
• Setup section: %BeginSetup, %EndSetup
• PageSetup section: %BeginPageSetup, %PageBoundingBox, %EndPageSetup.
• Other sections: %BeginProlog, %EndProlog, %Page, %Trailer, %EOF

Here is an example sequence showing how this function might be used:

let surface = Cairo.PS.create filename width height in
...
Cairo.PS.Dsc.comment surface "%%Title: My excellent document";
Cairo.PS.Dsc.comment surface
  "%%Copyright: Copyright (C) 2006 Cairo Lover";
...
Cairo.PS.Dsc.begin_setup surface;
Cairo.PS.Dsc.comment surface "%%IncludeFeature: *MediaColor White";
...
Cairo.PS.Dsc.begin_page_setup surface;
Cairo.PS.Dsc.comment surface "%%IncludeFeature: *PageSize A3";
Cairo.PS.Dsc.comment surface
  "%%IncludeFeature: *InputSlot LargeCapacity";
Cairo.PS.Dsc.comment surface "%%IncludeFeature: *MediaType Glossy";
Cairo.PS.Dsc.comment surface "%%IncludeFeature: *MediaColor Blue";
... (* draw to first page here *) ...
Cairo.show_page cr;
...
Cairo.PS.Dsc.comment surface "%%IncludeFeature: *PageSize A5";
...